Mystery Port

[PolarisCobra]

I recently bought a 2019 Bullet 272 BHS. There is a port on the door side, near the back, just in front of the door that goes into the bathroom. I thought if was for a black tank flush, but that is not the case.

It goes through the wall, and connects to a pipe that goes up to the sink faucet, see pics.

Can anyone explain what this port is for?

Note, pic 2 & 3 should be rotated 90 degrees to the right.

[RollaMo]

Originally Posted by PolarisCobra

I thought if was for a black tank flush, but that is not the case.

Are you sure?
Pic 3, follow that white water line up to the top behind the sink.

To me, it looks like the typical black tank flush lines that go up to the
Anti Siphon Valve like this:

[PolarisCobra]

It makes sense to me that it is a black tank flush. But - if it goes to an anti-syphon valve valve in the bathroom sink, how does it get to the black tank. Doesn't the bath sink connect to the grey tank?

[RollaMo]

Originally Posted by PolarisCobra

It makes sense to me that it is a black tank flush. But - if it goes to an anti-syphon valve valve in the bathroom sink, how does it get to the black tank. Doesn't the bath sink connect to the grey tank?

Well, you need to look up there and see exactly what is there.

If it is a black tank flush line, it does not actually connect to any sink lines.
It is just located up behind the sink to get it up higher.
In your picture number 3, you have two white lines a red line and a blue line showing.

Red = Hot water line to sink faucet
Blue = Cold water line to sink faucet

Those white lines, 1 up to the anti-syphon valve, and the second one coming back down from the valve to the black tank.

[PolarisCobra]

OK - That makes sense. The line from the port goes to anti-syphon, and down to the black tank. Has nothing to do with sink, except being routed close to it.

Would have been nice if they had labelled it...

Thanks.

[Martian]

While you are tracing that line, if it is the black tank flush you want to remove and replace that back flow preventer. They are awful when working properly and usually leak. Do not use the same type!
Here is part of the solution. Add a real check valve like a Sharkbite and you will be all set.

[Cheesehead4Life]

Check valves do not offer the same protection as anti-siphon. Stick with an anti-siphon device.